From then until the season closes March 31, hundreds of fishermen will scour oyster bars in the Chesapeake Bay and its tributaries for the prized bivalves. Here are five things to know as the annual catch gets underway.

Tangier Sound stays productive

Despite a 25 percent decline in the oyster catch in Tangier Sound and its tributaries, the 2014-2015 season remained among the most productive in recent years, according to the Maryland Department of Natural Resources.

The 180,773 bushels caught in the region's waters marked the third-largest total since diseases decimated the fishery in the late-1980s.

The annual haul plummeted sharply in certain areas around Tangier, falling by nearly half in Lower Tangier Sound, Fishing Bay and Pocomoke Sound. One of the few expanses to see a significant increase in dredging and tonging was the Manokin River, which increased its catch 69 percent to more than 3,100 bushels.

Bay-wide oyster catch dips slightly

There is more mixed news as the lens widens to all of Maryland's waters.

Fishermen raked in more than 388,000 bushels of oysters in the Chesapeake and its tributaries, down about 6 percent from the previous year. But that was good enough to rank as the second-biggest catch since 1998-1999.

Prospects for future population growth improve a little

Last fall's Maryland oyster survey found a rise in the density of baby oysters, known as spats, on the 53 bars surveyed. The spat concentration was three times higher compared with 2014. But it was less than half the total uncovered in 2010 and a little more than half the amount seen in 2012, both historically productive years.

Buy Photo

A pile of oysters harvested from the Nanticoke River.(Photo: File photo)

The quality of a season's oyster reproduction is generally reflected in the commercial catch two or three years later, when those surviving babies have grown into adults.

Are oyster sanctuaries working?

It is still "too early to know" whether oyster bars placed off-limits to fishing in 2010 are healthier than their counterparts that are routinely harvested, Natural Resources scientists said in a highly anticipated report over the summer.

But early indications are encouraging. Since 2010, the biomass — which accounts for the number and weight of all animals — nearly tripled in oyster sanctuaries. From 2010 to 2013, the amount of oysters grew in waters open to harvesting, but their numbers have dropped sharply since then.

Scientists suspect the higher abundance of larger, more-mature oysters in sanctuaries is fueling better reproduction by providing spots for floating oyster larvae to attach and grow.

The publicly fished areas probably benefited from the strong 2010 and 2012 reproduction cycles. Lacking adult oysters to offset the poorer reproduction that followed, though, the harvested bars couldn't sustain the growth in population the way the protected bars did, scientists suggest in the report.

Oyster management is changing

The state is five years into an unprecedented campaign to rebuild the oyster's population in the bay. Gov. Larry Hogan's administration is using the milestone to review the progress that's been made so far — and change some management strategies.

Meeting for the first time since Hogan took office in 2014, the Oyster Advisory Commission recently voted to restart restoration work in the Tred Avon River, which feeds into the Choptank River.

Commission members are considering which two tributaries the state should restore next. All three of the initial projects — the Tred Avon, Harris Creek and the Little Choptank River — were on the mid-Shore.

The board also may significantly revise the sanctuary strategy, officials say.

Watermen may be allowed to fish in areas once off-limits to tongs and dredges on a rotational basis. Commission members agreed at their latest meeting to get harvest and restoration ideas from the state's 11 county oyster committees.